The unmistakable trend for the tomorrow's flowmeter technology is the emergence of multiple function flowmeters which measure the mass and volume flow rates as well as the density of the fluid. The Pitot tube has been in use for nearly a hundred years, that determines the dynamic pressure of the fluid flow which is equal to one half of the fluid density times the square of the fluid velocity as the difference between the total pressure and the static pressure of the fluid. The vortex flowmeter, that determines the fluid velocity from the vortex shedding frequency, has become one of the most popular devices in the industrial flow measurements in only fifteen years after its introduction to the industry in mid-seventies. Previously, the inventor of the present invention has invented two different types of the mass-volume flowmeter. One type employs a vortex generating bluff body of a cylindrical shape disposed across a flow passage and a vortex sensor of planar shape disposed downstream of the vortex generating bluff body, wherein the volume flow rate is determined from the frequency of an alternating fluid dynamic force associated with the vortex shedding and experienced by the vortex sensor, and the dynamic pressure of the fluid flow is determined from the amplitude of the alternating fluid dynamic force, which teachings appears in U.S. Pat. No. 4,807,481. Of course, the mass flow rate is obtained from the ratio of the dynamic pressure to the volume flow rate and the density of the fluid is obtained as the ratio of the mass flow rate to the volume flow rate. The other type of the mass-volume flowmeter invented by this inventor employs a pair of parallel flow passages wherein one of the two flow passages includes a variable position flow obstructing body such as a flap or spherical member. The dynamic pressure of the fluid flow on the flow obstructing body opens up the flow passage under obstruction and, consequently, the degree of the obstruction decreases as the dynamic pressure of the fluid flow increases. The volume flow rate is determined as the sum of two signals generated by two volume flow sensors respectively disposed in the two flow passages, while the dynamic pressure of the fluid flow is determined as a function of level of inequality in the flow rate between the two flow passages by using an empirically obtained functional relationship therebetween, which teaching appears in U.S. patent application Ser. No. 07/208,739. The third most logical method for constructing a mass-volume flowmeter is to incorporate the operating principles of the Pitot tube into a vortex shedding flowmeter, which teaching is addressed by the present patent application.